JP2005536347A - Filter media containing fibers - Google Patents

Abstract

The improved filtration media or filter body can be made from fine fibers and can be formed into a filtration structure free of internal defects. The filter media or filter body comprises a collection of spots in a fiber having a defined fiber diameter, layer thickness, and media solidity. The fine fiber is formed in the media body and obtains a considerable flux and filtration efficiency. The filtration media or body can comprise a single layer or multiple layers of fine fibers coupled to an improved filter body.

Description

  The present invention relates to media, filter arrangements and methods. More specifically, the present invention relates to an arrangement for filtering particulate material from a fluid stream such as a gas stream or a liquid stream, such as air or a water-soluble stream. The invention also relates to a method of achieving the desired removal of particulate material from such a fluid stream. The present invention relates to an improved filter medium or structure that uses an improved fine fiber medium. The present invention more preferably relates to a fiber filter material that can be manufactured in a “defect free” structure and that can maintain an effective filtration capacity for a significant period of time.

  This application is filed on August 5, 2003 by Donaldson Company, Inc., a US company and US resident (applicant to all countries). The US patent application 10/225561 filed on August 20, 2002 and US patent application 10/411567 filed on April 7, 2003. Claimed and filed as a PCT international patent application.

  Fluids, ie liquid and gaseous streams, often carry entrained particulate material. In many cases, substantially removing some or all of the particulate material from the fluid stream is important for reasons including safety and health, machine operation, and aesthetics. For example, air intake flows to motor driven vehicle or generator engines, gas turbine flows, and air flow to various combustion furnaces often contain entrained particulates. When the particulate material reaches the internal working area of the various mechanisms involved, considerable damage can occur. In other cases, the gas produced or exhausted from an industrial process may contain particulate material therein, such as particles generated in the process. It may be required to substantially remove particulate material from their streams before directing such gases through various downstream devices and / or to the atmosphere. Various air filter or gas filter configurations have been developed to remove particulates using arrays of various forms of media material.

  Typically, the filter media material is used in a filtration structure located in the fluid path. The medium typically physically separates the particulates from the fluid stream. The medium is usually mechanically stable compared to the others and has serious mechanical properties because it has adequate permeability, a relatively small pore size, a small pressure drop, and resistance to fluid effects. Particulates can be effectively removed from the fluid over a period of time without causing media failure. The media can be made from several materials in woven or non-woven form. Such materials can be air-laid, water laid, melt blown, or otherwise effective pore size, porosity, solid Can be formed into sheet-like materials with specific or other filtration requirements.

  Non-woven filter elements can be used as surface packing media. In general, such elements include a dense mat of cellulose, glass, PTFE, synthetic fibers or other fibers oriented across the flow carrying particulate material. The media is generally permeable to the gas flow and has a sufficiently fine pore size and adequate porosity to prevent particles larger than the selected size from passing through the media. Built to have. As the material passes through the filter paper, the upstream side of the filter paper operates by diffusion and blocking to collect and retain particles of a selected size from the gas (fluid) stream. The particles are collected as a dust cake upstream of the filter paper. Over time, the dust cake also begins to act as a filter, increasing efficiency. This is sometimes referred to as “seasoning”, ie, deployment of efficiency that is superior to the initial efficiency.

  Media types useful in air cleaner systems, including some using the principles disclosed herein, include foams such as BASF Corporation (Wyandot, Michigan) or 3M (St. Paul, Minnesota). There are opencell foam media such as polyurethane foam media available from suppliers, and in some cases microporous media. For example, W.W. L. Gore and Associates, Inc. Expanded polytetrafluoroethylene comprising nodes interconnected by fibrils of the type generally manufactured by or under the supervision of [Newark, Delaware] and sold under the name Gore-Tex® (PTFE) membrane, and Donaldson Company Inc. PTFE material manufactured by Tetratec, a division of the company and sold under the trade name Tetratex®, is a microporous membrane. Techniques for producing such microporous membranes are generally provided in US Pat. Nos. 3,953,566, 4,187,390, 4,110,239, and 5,066,683, which are incorporated herein by reference. . Often, such membranes are used in the construction of air cleaner filters, the membrane is laminated to a substrate such as a scrim, or the membrane is between various substrates, such as two layers of felt or scrim. Be placed. In general, PTFE membranes or similar microporous membranes act as surface filling or barrier filters. On the other hand, open cell foam membranes usually operate as depth media.

Other media used in filtration equipment include the use of glass fibers. Such glass fiber media is typically a relatively small diameter glass fiber composed of a woven or non-woven structure that has considerable resistance to chemical attack, and is relatively common in filter cartridge applications. Can have low porosity and high efficiency (HEPA). Such glass fiber media can be found in the following US patent numbers: Smith et al., US Pat. No. 2,797,163, Wagoner, US Pat. No. 3,228,825, Raczek, US Pat. No. 3,240,663, Young et al., US Pat. No. 3,249,491. Bodendorf et al., US Pat. No. 3,253,978, Adams et al., US Pat. No. 3,375,155, and Pews et al., US Pat. No. 3,882,135. Other filtration media use spaced fine fiber structures and are incorporated herein by reference, Donaldson US Pat. No. 5,672,399, and incorporated herein by reference. Characterized in commonly assigned US patent application Ser. No. 08 / 935,103, filed Sep. 29, 1997. Such a material can be viewed as a hybrid between a depth media type structure and a surface-filled structure. That is, the particles are distributed through such a structured depth, but each of the fine fiber layers generally operates in part as a barrier form, and in some cases, the spacing material is predominantly fine. Operates to separate the fiber layers and allow for filling. Such media can also be used in selection configurations that include the principles characterized herein.
U.S. Pat. No. 3,953,566 US Pat. No. 4,187,390 U.S. Pat.No. 4,110,239 US Pat. No. 5,066,683 U.S. Pat. No. 2,797,163 U.S. Pat. No. 3,228,825 U.S. Pat. No. 3,240,663 U.S. Pat. No. 3,249,491 US Pat. No. 3,253,978 US Pat. No. 3,375,155 U.S. Pat. No. 3,882,135 US Pat. No. 5,672,399 US patent application 08/935103

We have found that effective filter media can be made by forming the filter media from a polymer material and forming the fibers into a relatively thick collection of fine fibers. The fine fiber of the layer preferably has a diameter of about 0.01 to about 1 μm, preferably about 0.03 to 0.5 μm. The layer comprising the fiber has a thickness of about 1 to 100 μm and a media solidity of about 5% to 50%, preferably about 5% to 30%. The polymer filter media of the present invention is made from organic polymer materials other than perfluorinated polymers. These media can be used to filter fluids, including gas and liquid fluids. Preferred media of the present invention are substantially capable of maintaining a thickness of about 5 to 100 μm and a substantial filter life greater than about 10 mL / min / cm ² (10 mL-min ⁻¹ -cm ² ) at 10 psi of water. With a flux of. In one aspect of the media of the present invention, the media solidity can be about 7% to 25% when used to filter fluids and can be 10 mL / min / cm ² (at 10 psi). At least about 98% for particles of about 0.2 μm when tested at a flux greater than 10 mL-min ⁻¹ -cm ² ) and a flow rate of about 20 mL / min / cm ² of water. Test filtration efficiency.

The media of the present invention typically builds the thickness of the media using multiple steps by forming fine fibers into a relatively thick media layer in a single step, or by an electrostatic spinning process. Is formed by. The formed filter mat is then subjected to temperature and pressure conditions that can compress the layer into a mechanically stable media layer having substantially defect-free properties that can effectively remove particulates from the fluid stream. Expose to. In the present invention, the term “defect free” means that when a filter element or cartridge is made using the media of the present invention, the media can remove a significant amount of particulates from the fluid flow, It means that no failure occurs by passing the microparticles through a defect path having a pore size significantly larger than the pores formed in the process. In the present invention, the medium has a filtration efficiency of about 98% for particles of about 0.2 μm at a flow rate of about 20 mL-min ⁻¹ -cm ² of water. Any deep path that reduces the efficiency of the media below this parameter constitutes a defect path.

  The invention also relates to polymeric materials that can be produced with improved environmental stability against heat, humidity, reactive materials, and mechanical stress. Such materials can be used to form microfibers such as microfiber materials and nanofiber materials used in the media of the present invention with improved stability and strength. As the fiber size is reduced, material survivability becomes even more problematic. Such fine fibers are useful in a variety of applications. In one application field, the filter structure can be prepared using this fine fiber technology. The present invention relates to polymers, polymer compositions, fibers, filters, filter construction, and filtration methods. The application of the present invention specifically relates to filtering particles from fluid streams, such as from air streams and liquid (eg, non-aqueous and aqueous) streams. The described technique relates to a structure having one or more layers of fine fibers in a filter medium. Composition and fiber size are selected for a combination of properties and persistence.

  The filter media includes at least a microfiber or nanofiber media layer that is optionally combined with a substrate material or porous support in a mechanically stable filter structure. These layers combine excellent filtration with minimal flow restriction and high particle collection efficiency when a fluid such as a gas or liquid passes through the fine fiber filter media of the present invention. The media of the present invention can be located upstream, downstream, or in an inner layer of the fluid flow. Various industries have recently been of great interest in using filtration media for filtration, ie removing unwanted particles from a fluid such as a gas or liquid. Common filtration processes remove particulates from fluids, including air streams or other gas streams, or from liquid streams such as hydraulic fluids, lubricants, fuels, water streams, or other fluids. Such a filtration process requires the mechanical strength and chemical and physical stability of the microfiber and substrate material. The filter media can be exposed to a wide range of temperature conditions, humidity, mechanical vibrations and shocks, and reactive and non-reactive, abrasive or non-abrasive particulates can enter the fluid stream. Furthermore, filtration media often can remove self-cleaning ability from subjecting the filter media to reversal pressure pulses (short reversal of fluid flow to remove the surface coating of particulates) or contaminating particulates from the surface of the filter media. Requires another cleaning mechanism that can. Such reversal cleaning can result in a greatly improved (ie) reduced pressure drop after pulse cleaning. Particle collection efficiency is not usually improved after pulse cleaning, but pulse cleaning reduces pressure drop and saves energy in the filtration operation. Such a filter can be removed for repair and cleaned in an aqueous or non-aqueous cleaning composition. Such media are often manufactured by spinning microfibers and then forming a microfiber interlocking web on a porous substrate. In the spinning process, the fibers can form physical bonds between the fibers so that the fiber mat engages in the integration layer. Such materials can then be fabricated into desired filter formats such as cartridges, flat disks, canisters, panels, bags, and pouches. Within such a structure, the media can be substantially pleated, rolled, or otherwise placed on a support structure.

  Polymer nanofibers and polymer microfibers are known, but their use is very fragile due to their mechanical vulnerability and the high surface area to volume ratio, which makes them susceptible to chemical degradation. It was limited. The fibers described in the present invention are useful in a wide variety of filtration, fabrics, membranes, and various other applications by addressing these limitations. The filter should retain the ability to filter and load the fiber matrix into the fiber matrix during filtration, while maintaining the actual flow rate or overspeed and acceptable pressure drop.

  The “lifetime” of a filter is usually defined according to a selected limiting pressure drop across the filter. The pressure increase across the filter defines the lifetime at a level defined for the field of application or design. Since this pressure increase is a result of filling, longer life is usually directly related to higher capacity in systems of comparable efficiency. Efficiency is the tendency of a medium to collect particulates rather than let them pass. In general, it is clear that the filter media generally approaches the “life” pressure differential more quickly as the filter media removes particulates more efficiently from the gas stream (if other variables are held constant). Suppose).

  As used herein, the term “filter element” is generally intended to refer to a portion of an air cleaner that includes a filter media therein. The filter element provides mechanical separation of the particulates from the fluid. In general, the filter element is designed as a removable and replaceable or repairable part of the air cleaner. That is, the filter media is carried by the filter element and is separable from the rest of the air cleaner, thereby removing the filled or partially filled filter element and making it new or It can be regenerated by replacing it with a cleaned filter element. The air cleaner is preferably designed so that it can be removed and replaced by hand. The term “filter medium” or “media” refers to a material or collection of materials through which a fluid passes, and particles are incidentally and at least temporarily deposited in or on the medium.

  The conventional media discussed above had adequate performance for the assigned role in the filtration equipment and process. However, all of these media include back pressure or pressure drop in use, relatively large pore size, permeability issues, and other issues regarding the flow rate of material through the filter over the filter life. Affected by various problems. The art reduces effective pore size and increases the range of particulates that can be filtered from air and gas streams while providing high permeability, long service life, and controllable pressure drop There is an essential need to improve the filter media by maintaining

  The filter media of the present invention can be used in virtually any field of application involving the filtration of fluids, including gas and liquid streams. The material can be used to remove various particulate matter from the stream. The particulate material can include both organic or inorganic contaminants. Organic contaminants can include large particulate natural products, organic compounds, polymer particulates, food residues, and other materials. Inorganic residues can include dust, metal particulates, ash, smoke, mist, and other materials.

  The filtration media of the present invention can be used in virtually any conventional structure, including flat panel filters, elliptical filters, cartridge filters, spiral wound filter structures, and form the media in useful shapes or profiles Can be used in pleated Z-filters or other geometric structures.

  The present invention relates to filter media, filter elements, filter cartridges, or other filter technologies comprising fine fiber filter media. The microfiber filter media comprises substantially organic polymer microfibers that are substantially free of perfluorinated polymer material with a collection of fibers in the media layer, the fibers having a diameter of about 0.03 to 0.5 μm. A thickness of about 1 to 100 μm and a solidity of about 5% to 50% or about 5% to 30%. Increased solidity allows the thickness to be reduced without significantly reducing efficiency or other filter characteristics. By increasing the solidity to a limit of up to about 50% at a constant thickness, pore size is reduced and particulate storage is increased. Such filter media technology can be used in a variety of filtration methods to remove particulates from a fluid stream, particularly from a liquid that is preferably an aqueous stream.

Microfibers comprising microfibers or nanofibers containing layers of the present invention can be fibers and can have a diameter of about 0.01 to 2 μm, preferably 0.03 to 0.5 μm. The thickness of a typical fine fiber filtration layer is about 0.1 to 100 times the fiber diameter, solidity with a basic weight of about 5 to 35 μm · cm ⁻² and a volume of up to 50%. (Solidity).

  Improved polymeric materials have improved physical and chemical stability. Polymer fine fibers can be made into useful product formats. A nanofiber is a fiber having a diameter of less than 200 nm or 0.2 μm. A typical medium has a fiber diameter greater than about 1 μm. The microfiber can be made in the form of an improved single layer or multiple layer microfiltration media structure. The fine fiber layer of the present invention comprises a random distribution of fine fibers that can be joined to form an interlocking net. Filtration performance is primarily obtained as a result of fine fibers processing the fluid and establishing a barrier to the passage of particulates. Stiffness, strength, and pleated structural properties are provided by the substrate to which the fine fibers are bonded. Microfiber meshing networks have, as important properties, microfibers in the form of microfibers or nanofibers, and a relatively small space (pore size) between the fibers. Such spaces are typically in the range of about 0.01 to about 25 μm, or often about 0.1 to about 10 μm between the fibers. The filter product comprises a fine fiber layer and an optional support or other media layer. In service, the filter can stop the attendant particulates from passing through the fine fiber media layer and achieve a substantial surface packing of the collected particles. Particles with dust or other attendant particulates quickly form a dust cake on the surface of the fine fiber and maintain a high initial and overall efficiency of particulate removal. Even with relatively fine contaminants having a particle size of about 0.01 to about 1 μm, filter media with fine fibers have a very high dust capacity.

  The microfiber media of the present invention comprises a virus that may have a dimension of about 0.005 to about 0.02 μm, a tobacco smoke that may have a particle size in the range of about 0.01 to about 1 μm, about 0.0. Household dust having a particle size in the range of 5 up to 100 μm, bacteria having a particle size in the range of about 0.03 to about 20 μm, household dust that can be in the range of about 0.1 to about 100 μm And can be successful in collecting particles as small as other harmful or undesirable particulate materials. The effective filter activity of the media of the present invention can appear in small particles from 0.02 μm up to 100 μm and beyond.

  The polymeric materials disclosed herein are resistant to the undesired effects of heat, humidity, high flow rates, reversal pulse cleaning, operational attrition, submicron particulates, used filter cleaning, and other necessary conditions. , With greatly improved resistance. The improved microfiber and nanofiber performance is a result of the improved properties of the polymer material that forms the microfiber or nanofiber. In addition, the filter media of the present invention using the improved polymeric material of the present invention provides high efficiency, lower flow restriction, high durability in the presence of milled particulates (stress related or environmental related). It provides several advantageous features, including a smooth outer surface free of free fibers or fibrils. The overall structure of the filter material provides an overall thinner media, thereby improving the media area per unit volume, reduced speed through the media, improved media efficiency, and reduced flow. Can be limited. Preparing the media of the present invention from fine fibers provides high quality fine fiber filtration activity in a media structure that can be easily handled and assembled into a filter structure, while providing a small fiber size, small pore size, A media layer having a high depth made entirely from fine fibers that maintain high permeability and acceptable solidity is provided.

  Polymers used in the media include polyethylene and polypropylene, nylon, PVC, PET, PBT and other polyesters, polyether sulfone, PVDF, polycarbonate, styrene polymers and copolymers, and others.

  A preferred mode of the invention is a polymer mixture comprising a first polymer and a second different polymer (different in polymer type, molecular weight, or physical properties) that is conditioned or treated at elevated temperatures. The polymer mixture can be reacted to form a single chemical species or can be physically bonded to the mixed composition by an annealing process. Annealing imposes physical changes, similar crystallinity, stress relaxation, or orientation. Preferred materials are chemically reacted to a single polymer species so that differential scanning calorimetry analysis will reveal a single polymer material. When such a material is combined with a preferred additive material, it can form a surface coating of the additive on the microfiber, which when contacted at high temperatures, high humidity, and different operating conditions, Provides oleophobicity, hydrophobicity, or other related improved stability. Such microfibers may have a smooth surface comprising a discrete layer of additive material, or an outer coating of additive material partially solubilized or alloyed, or both on the polymer surface. Preferred materials used in the mixed polymer system include nylon 6, nylon 66, nylon 6-10, nylon (6-66-610) copolymers, and other chained general aliphatic nylon compositions. A preferred nylon copolymer resin (SVP-651) was analyzed for molecular weight by end titration. (JE Walz and GB Taylor, determination of the molecular weight of nylon, Anal. Chem. Vol. 19, Number 7, pages 448-450 (1947)). Some average molecular weights (Wn) were between 21,500 and 24,800. This composition was estimated by a phase diagram of the three component nylon melting temperatures, about 45% nylon 6, about 20% nylon 66, and about 25% nylon 610. (Page 286, Nylon Plastics Handbook, edited by Melvin Kohan, Hanser Publisher, New York (1995)).

  Polyvinyl alcohol having a degree of hydrolysis greater than 87 to 99.9% can be used in such polymer systems. These are preferably cross-linked. Most preferably, it is crosslinked and combined with a significant amount of additional material that is oleophobic and hydrophobic.

  Another preferred mode of the invention includes a single polymer material combined with an additive composition to improve the lifetime or operating characteristics of the fiber.

  Particularly preferred materials of the present invention comprise fiber material having a dimension of about 0.1 to 1 μm. The most preferred fiber size range is 0.03 to 0.5 μm. Such a fiber having a preferred size provides excellent filter activity, easy back pulse cleaning, and other aspects. In such a mode, the polymer material must be attached to the substrate while receiving a pulse clean input that is approximately equivalent to normal filtration conditions except for the inversion direction across the filter structure. Such adhesion can be the result of a solvent effect of fiber formation when the fiber is contacted with the substrate, or a post-treatment of the fiber on the substrate by heat or pressure. However, polymer properties play an important role in determining adhesion, such as certain chemical interactions such as hydrogen bonding, polymer-substrate contact that occurs at temperatures above or below Tg, and polymer formulations that contain additives. It seems to fulfill. Polymers plasticized with solvent or flow during bonding can have increased adhesion.

  An important aspect of the present invention is the usefulness of such microfiber or nanofiber materials formed into filter structures. In such a structure, the microfiber material of the present invention acts as a separate medium for the filter. Other media can also be used in the filter with the fine fiber media. Non-woven, non-woven and woven glass cloth, extruded and perforated made from natural fiber and synthetic fiber substrates, analogs of spun-bonded cloth, synthetic fiber nonwovens, cellulose derivatives, synthetic fibers, and glass fiber blends Plastic screen-like materials, organic polymer UF membranes and MF membranes can be used. A sheet-like substrate or cellulose derivative nonwoven web can then be formed into the filter structure, which includes fluid flow, including air or liquid flow, to remove suspended or contaminated particulate from the flow. Placed in. The shape and structure of the filter structure is left to the design engineer.

Polymeric materials that can be used in the polymer composition of the present invention include additions such as polyolefins, polyacetals, polyamides, polyesters, cellulose ethers and esters, polyalkylene sulfides, polyarylene oxides, polysulfones, modified polysulfone polymers, and mixtures thereof. Includes both polymer and condensation polymer materials. Preferred materials that fall into these generic classes include polyethylene, polypropylene, poly (vinyl chloride), polymethylmethacrylate (and other acrylic resins), polystyrene, and copolymers thereof (including ABA type block copolymers), There are polyvinyl alcohols of various degrees of hydrolysis (87% to 99.5%) in poly (vinylidene chloride), poly (vinylidene chloride), crosslinked and non-crosslinked forms. Preferred addition polymers tend to be glassy (at Tg above room temperature). This is the case when the crystallinity is low for polyvinyl chloride and polymethyl methacrylate, polystyrene polymer compositions, or alloys, or polyvinylidene fluoride and polyvinyl alcohol materials. One class of polyamide condensation polymers are nylon materials. The term “nylon” is a generic name for all long chain synthetic polyamides. Normally, the name of nylon, starting material (pointing to the first digit C ₆ diamine, second digit refers to C ₆ dicarboxylic acid compound) C ₆ diamine and C _{6 2} acid (diacid) indicates a Includes a series of numbers, such as nylon 6,6. Other nylons can be made by polycondensation of epsilon caprolactam in the presence of a small amount of water. This reaction forms nylon 6, a linear polyamide (made from cyclic lactam, also known as epsilon-aminocaproic acid). In addition, nylon copolymers are also contemplated. Copolymers can be made by combining various diamine compounds, various diacid compounds, and various cyclic lactam structures in the reaction mixture, and then forming nylon into a random configuration monomer structure of polyamide structure. it can. For example, nylon 6,6-6,10 material is a nylon manufactured from a mixture of _{C 6} and _{C 10} of hexamethylenediamine and diacid (diacid). Nylon 6-6,6-6,10 is epsilon amino caproic acid, hexamethylenediamine, and a nylon manufactured by copolymerization of a mixture of diacid (diacid) material _{C 6} and _{C 10.}

  Block copolymers are also useful in the process of the present invention. For such copolymers, the choice of solvent swelling agent is important. The solvent chosen is such that both blocks are soluble in the solvent. An example is ABA (styrene-EP-styrene) polymer or AB (styrene-EP) polymer in methylene chloride solvent. If one component is not soluble in the solvent, it forms a gel. Examples of such block copolymers include Kraton® type of styrene-b-butadiene and styrene-b-hydrogenated butadiene (ethylenepropylene), e-caprolactam-b-ethylene oxide Pebax ( There are Pebax (R) type, Sympatex (R) polyester-b-ethylene oxide, and polyurethanes of ethylene oxide and isocyanate.

  Addition polymers such as polyvinylidene fluoride, syndiotactic polystyrene, copolymers of vinylidene fluoride and hexafluoropropylene, amorphous addition polymers such as polyvinyl alcohol, polyvinyl acetate, poly (acrylonitrile) and copolymers with acrylic acid and methacrylate, polystyrene, Poly (vinyl chloride) and its various copolymers, poly (methyl methacrylate) and its various copolymers are soluble at low pressure and low temperature and can be solution-spinned relatively easily. However, highly crystalline polymers such as polyethylene and polypropylene require high temperature, high pressure solvents when solution spinning. Therefore, solution prevention of polyethylene and polypropylene is very difficult. Electrostatic solution spinning is one method of making nanofibers and microfibers.

  We have also found great advantages in forming a polymer composition comprising two or more polymer materials in a polymer mixture, alloy format, or cross-linked chemical bond structure. Such polymer composition can be achieved by altering the attributes of the polymer, such as improving polymer chain flexibility or chain mobility, increasing overall molecular weight, and providing reinforcement by forming a network of polymer materials. It is thought to improve physical properties.

  In one embodiment of this concept, two related polymer materials can be mixed for advantageous properties. For example, high molecular weight polyvinyl chloride can be mixed with low molecular weight polyvinyl chloride. Similarly, high molecular weight nylon materials can be mixed with low molecular weight nylon materials. In addition, different species of common polymer families can be mixed. For example, a high molecular weight styrene material can be mixed with low molecular weight, high impact polystyrene. The nylon 6 material can be mixed with nylon copolymers such as nylon 6; 6,6; 6,10 copolymers. In addition, polyvinyl alcohol with low hydrolysis, such as 87% hydrolyzed polyvinyl alcohol, is fully hydrolyzed or superhydrolyzed with a degree of hydrolysis between 98 and 99.9% and higher. Can be mixed with polyvinyl alcohol. All of these materials in the mixture can be crosslinked using a suitable crosslinking mechanism. Nylon can be crosslinked using a crosslinking agent that reacts with amide-bonded nitrogen atoms. Polyvinyl alcohol materials include hydroxyl reactive materials such as monoaldehydes such as formaldehyde, urea, melamine formaldehyde resins and the like, boric acid and other inorganic compounds, dialdehydes, diacids, urethanes, epoxies, and other Crosslinking can be performed using known crosslinking agents. Cross-linking techniques are well known and the phenomenon of forming covalent bonds between polymer chains is understood so that the cross-linking reagents react to greatly improve molecular weight, chemical resistance, overall strength, and resistance to mechanical degradation. ing.

  We have found that additive materials can significantly improve the properties of polymer materials in the form of fine fibers. Resistance to the effects of heat, humidity, impact, mechanical stress, and other negative environmental effects can be greatly improved by the presence of additional materials. When we process the microfibers of the present invention, additional materials can improve the oleophobic character, hydrophobic properties, and help improve the chemical stability of the material I found that I can do it. The microfibers of the present invention in the form of microfibers are improved by the presence of these oleophobic and hydrophobic adducts because these adducts are protective layer coatings, abrasive surfaces This is thought to be because it penetrates the surface to a certain depth so as to form or improve the properties of the polymer material. An important property of these materials is believed to be the presence of strongly hydrophobic groups that are preferably capable of also having oleophobic properties. Strongly hydrophobic groups include fluorocarbon groups, hydrophobic hydrocarbon surfactants or blocks, and approximately hydrocarbon oligomer compositions. These materials are manufactured into compositions having some of the molecules that tend to be compatible with polymer materials that normally provide physical association or association with the polymer, while as a result of the association between the adduct and the polymer. The hydrophobic groups or oleophobic groups form a protective surface layer that is on the surface or alloyed or mixed with the polymer surface layer. For a 0.2 μm fiber with an adduct level of 10%, the surface thickness is calculated to be about 50 mm when the adduct is migrating towards the surface. Migration is believed to occur due to the non-existence of oleophobic or hydrophobic groups in the bulk material. A thickness of 50 mm appears to be a reasonable thickness for the protective coating. For a 0.05 μm diameter fiber, a thickness of 50 mm corresponds to a mass of 20%. For a 2 μm thick fiber, a thickness of 50 mm corresponds to a mass of 2%. The additive material is preferably about 2 to 25 wt. Used in the amount of%. Oligomer adducts that can be used in combination with the polymeric material of the present invention include from about 500 to about 5000, preferably from about 500, including fluorochemicals, nonionic surfactants, and low molecular weight resins or oligomers. There are oligomers having a molecular weight of about 3000. Fluorinated organic wetting agents may also be useful in the present invention.

  In addition, nonionic hydrocarbon surfactants, including lower alcohol ethoxylates, fatty acid ethoxylates, nonylphenol ethoxylates, and the like can also be used as additional materials of the present invention. Examples of these materials include Triton X-100 and Triton N-101.

  A useful material used as an additional material in the composition of the present invention is a tertiary butylphenol oligomer. Such materials tend to be relatively low molecular weight aromatic phenolic resins. Such resins are phenolic polymers prepared by direct enzymatic oxidative coupling from aromatic rings to aromatic rings. The absence of methylene bridge provides inherent chemical and physical stability.

  Examples of these phenolic materials include Enzymomol International Inc. There are Enzo-BPA / phenol, Enzo-TBP, Enzo-COP, and other related phenols obtained from Columbus, Ohio.

  With respect to the media geometry, the preferred geometry is usually a pleated cylindrical pattern. Such cylindrical patterns are generally preferred because they are relatively simple to manufacture, use conventional filter manufacturing techniques, and are relatively easy to service. By pleating the medium, the surface area placed within a given volume is increased. In general, the main parameters for such media placement are the pleat depth, the density of the pleats, usually measured in pleats per inch along the inner diameter of the pleated media cylinder, and the length or pleat length of the cylinder. Length. In general, particularly for barrier (non-hybrid) configurations, the primary factor for media pleat depth, pleat length, and pleat density selection is the total surface area required for a given application or situation. Such principles generally apply to the media of the present invention and preferably to similar barrier type arrangements.

  As pointed out in US Pat. No. 5,423,892, a depth media system, or a system using a combination of barrier media and depth media, is less constrained in terms of geometry than a strict barrier system. See, for example, US Pat. No. 5,423,892, column 18, line 60 to column 21, line 68. In general, however, in the past, such configurations, particularly with respect to automotive filters, have the same size and shape as pleated media configurations of similar applications (at least about 66% and generally more than the same media volume). Usually have). Thus, if the entire media structure is placed between the inner and outer liners, the media volume is generally a cylindrical volume defined between the inner and outer liners, the same as noted above It can be calculated by the method.

  With regard to efficiency, the principles vary with respect to the type of media involved. For example, cellulose fibers or similar barrier media are generally altered in terms of efficiency by changing the overall porosity or overall permeability. Also, as described in U.S. Pat. Nos. 5,423,892 and 5,672,399, in some cases, by refueling the media, and in other cases, relatively fine fibers that are typically less than 5 μm, And in many cases, the efficiency of the barrier media can be modified by attaching submicron sized (average) fibers to the surface of the media. As described in US Pat. No. 5,423,892, for fibrous depth media configurations, such as dry fiber media, variables related to efficiency include the percent solidity of the media, the manner in which the media is compressed within the included configuration, overall Thickness or depth, and fiber size.

  Construction of the filter media according to the present invention involves securing a layer of fine fiber media to the filter structure.

The permeability of the first layer of fine fiber material, when evaluated is separated from the rest of the structure by Frazier permeability test, of at least 3.5 m-min ^-1, typically and preferably penetrate about 20 m-min ^-1 The material which shows sex is provided. In this specification, when referring to efficiency, unless otherwise noted, 20fl-m ⁻¹ (6.1 m-min ⁻⁾ using 0.78 μm monodisperse polystyrene spherical particles as described herein. ¹ ) means to refer to the efficiency when measured according to ASTM-1215-89.

  The above general description of various aspects of the construction of the polymeric material of the present invention, the microfiber material of the present invention, and the useful filter structure from the microfiber material of the present invention is a general technique of the operation of the present invention. Provides an understanding of the principles. Electrospinning of small diameter fibers less than 10 μm is obtained using an electrostatic force from a strong electric field that acts as a pulling force that stretches the polymer jet into very fine filaments. Although the molten polymer can be used in the electrospinning process, it is optimal that fibers smaller than 1 μm are made from the polymer solution. As the polymer mass is stretched to a smaller diameter, the solvent evaporates and contributes to fiber size reduction. The choice of solvent is important for several reasons. If the solvent dries too quickly, the fibers tend to be flat and large in diameter. If the solvent dries too slowly, the solvent will redissolve the formed fiber. It is therefore important to match the drying rate with the fiber formation. At high production rates, a large amount of exhaust air flow acts to prevent flammable atmospheres and reduce the risk of ignition. Solvents that are not flammable are useful. In a manufacturing environment, processing equipment requires cleaning as needed. Safe, low toxicity solvents minimize worker exposure to hazardous chemicals.

  A unit of microfiber or nanofiber can be formed by an electrospinning process. The electrospinning device includes a reservoir containing a fine fiber-forming polymer solution and a discharge device, and the polymer solution is pumped to the discharge device. The ejector device obtains the polymer solution from the reservoir and, as will be discussed below, in the electrostatic field, the solution droplets are accelerated by the electrostatic field toward the collection medium. Facing the ejector, but at an interval, a generally planar grid is disposed on which a collection media substrate or a combined substrate is disposed. Air can be drawn through the grid. The collection medium is placed in proximity to the grid. A high voltage electrostatic potential is maintained between the ejector and the grid, and the collection substrate is placed between them by a suitable electrostatic voltage source and connections connected to the grid and the ejector, respectively.

  In use, the polymer solution is pumped to the discharge device. The electrostatic potential between the grid and the discharge device imparts a charge to the material, so that the liquid is discharged from the discharge device as a thin fiber, and the fiber is drawn towards the grid and arrives at the grid, A sufficient amount is collected on the substrate to form one or more unit layers that are robust and mechanically stable. The filter media of the present invention is formed as one or more initial layers that are about 0.1 to 300, preferably 1 to 200 μm thick. In the case of a solution polymer, the solvent evaporates from the fiber during the transition to the grid, and therefore the fiber reaches the collection substrate. The fine fiber first couples to the substrate fiber encountered in the grid. The strength of the electrostatic field is selected to ensure that the polymer material itself is accelerated from the ejector to the collection substrate medium, and the acceleration is sufficient to make the material a very thin microfiber or nanofiber structure. It is. By increasing or decreasing the rate of progress of the collection medium, more or fewer drain fibers can be deposited on the forming medium, thereby controlling the thickness of each layer deposited thereon become. A sheet-like collection substrate is formed of fine fibers. The sheet substrate is then directed to a separation station and one or more fine fiber layers are removed from the substrate, if necessary, in continuous operation. If another layer is sent to a fine fiber spinning station to further form a continuous length of sheet substrate, the spinning device forms an additional fine fiber layer and filters this fine fiber. Arrange in layers. After the fine fiber layer is formed on the sheet-like substrate, the fine fiber layer and the substrate are sent to a heat treatment and pressure treatment such as a calendering station, and the fine fiber layer having a compressed thickness and basis weight is sent. Appropriate processing is performed to form the layer. The sheet substrate and fine fiber layer are then tested for QC in an appropriate station such as an efficiency monitor. The sheet substrate and fiber layer are then directed to a suitable filter manufacturing station or winding station and wound on a suitable spindle for further processing or subsequent filter manufacturing. .

  After processing the media of the present invention, the media comprises a single layer or multiple layers of fine fibers formed into a continuous sheet media structure. After processing is complete and the media is at final thickness, a single layer of media structure is about 0. A final depth from 1 to about 100 μm, preferably from about 1 to about 50 μm, and most preferably from about 1 to about 15 μm can be provided. For multi-layer structures, the overall final thickness can range from about 0.1 to about 100 μm, with each individual layer ranging from about 0.1 to about 100 μm, preferably from about 0.3 to about 50 μm. Having a thickness of The overall solidity, average pore size, permeability, and basic weight are as follows:

  One preferred configuration according to the present invention includes a generally defined filter medium in the overall filter construction. Some preferred configurations for such use comprise a medium configured in a cylindrical pleat configuration, the pleats extending generally in the longitudinal direction, ie in the same direction as the longitudinal axis of the cylindrical pattern. In such a configuration, the media can be embedded in the end cap, as in a conventional filter. Such a configuration can include an upstream liner and a downstream liner, if desired, for normal conventional purposes.

  In some applications, the media according to the present invention can be used with other types of media, such as conventional media, to improve overall filtration performance or lifetime. For example, media according to the present invention can be laminated to conventional media, used in a stack configuration, or incorporated into a media structure that includes one or more regions of conventional media (integral feature). is there. The media according to the present invention can be used upstream of such media for good filling and / or used downstream of conventional media as a high efficiency abrasive filter. Is possible.

  Certain configurations according to the present invention may also be used in liquid filter systems. That is, the specific material to be filtered is conveyed in the liquid. Also, certain configurations according to the present invention can be used in mist collection devices, such as configurations that filter fine mist from air.

  According to the present invention, a filtration method is provided. Advantageously, the process generally involves the use of the described medium for filtration. As can be seen from the following description and examples, it is advantageous that the media according to the present invention can be specifically configured and constructed to provide a relatively long lifetime in a relatively efficient system.

  Various filter designs are shown in patents that disclose and claim various aspects of one or more filter structures for use with filter materials. US Pat. No. 4,720,292 to Engel et al. Discloses a radial seal design for a filter assembly having a generally cylindrical filter element design, the filter element having a relatively flexible rubber having a cylindrical radially inward facing surface. It is sealed with an end cap. Kahlbaugh et al. US Pat. No. 5,082,476 discloses a filter design using a depth medium comprising a foam substrate having a pleated component combined with a microfiber material of the present invention. Stifelman et al US Pat. No. 5,104,537 relates to a filter structure useful for filtering liquid media. The liquid is entrained in the filter housing and travels through the outer surface of the filter into the inner annular core and then returns to active use on the substrate. Such a filter is very useful for filtration of hydraulic fluid. US Pat. No. 5,613,992 to Engel et al. Shows a conventional diesel engine air intake filter structure. The structure obtains air from the outer surface of the housing with or without contaminated moisture. Air passes through the filter, while moisture can travel to the bottom of the housing and be exhausted from the housing. Gillingham et al. US Pat. No. 5,820,646 discloses a Z filter structure. This uses a specific pleated filter design that includes a plug passage that requires fluid flow to pass through at least one layer of filter media in a Z-shaped path to obtain adequate filtration performance. Filter media formed in a pleated Z-format can include the fine fiber media of the present invention. Glen et al. US Pat. No. 5,853,442 discloses a bag house structure having a filter element that may include the fine fiber structure of the present invention. Berkhhoe et al., US Pat. No. 5,9554849, shows a dust collector structure. This is useful for processing normally air with a large amount of dust filling to filter the dust from the air stream after processing a workpiece that produces a large amount of dust filling in ambient air. Finally, Gillingham, US Design No. 425189 discloses a panel filter that uses a Z filter design.

  The above description of various aspects of the present invention provides a basis for understanding the structure of the fine fiber media in the filter structure of the present invention. The following examples and data further illustrate the functional properties of the present invention. The illustrated materials are specific embodiments of the present invention and are not intended to narrow the scope of the claims.

  As a basis for comparison, Millipore cellulose acetate and cellulose nitrate lines were characterized in terms of various operating parameters as shown in Table 1 below. These results showed both liquid and gas performance.

  Based on these data, an improved filter by reducing pore size by reducing fiber diameter while maintaining solidity, permeability, and pressure drop with increased tolerance I think I can create a medium. If the pore size distribution can be narrowed, thinner structures with equivalent separation characteristics can be produced as conventional Millipore membrane candidates with substantially increased flow rates.

  Tables 2 and 3 list the solidity enhancement and interfiber spacing results obtained by reducing the layer thickness at constant mass. By comparing Table 1 with Tables 2 and 3, reducing the layer thickness to 80 μm provides a mitered cylinder inter-fiber space comparable to a Millipore 0.22 membrane. It is done. Further calendering to a thickness of about 20 μm provides a space between the splicing cylindrical fibers close to the suggested manufacturer's pore grade. Similarly, a filtration structure having an average interfiber spacing of 0.5 μm and an average pore size of 0.19 μm at a solidity of 0.25 comparable to a Millipore 0.22 membrane increases the thickness from 150 to 40 μm. By reducing it, the flow rate was increased almost 4 times. In addition, if two 40 μm layers are joined, the separation efficiency can be improved to achieve about twice the flow advantage. Based on these models, to achieve the advantage of large flow rate with equal or improved efficiency with a calendered fine fiber matrix in a single or multi-layer structure I think you can. Tables 2 and 3 describe the calculation of improved media filter characteristics.

  The above specifications, examples, and data provide a complete description of the manufacture and use of the composition of the invention. Since many embodiments of the invention can be made without departing from the spirit and scope of the invention, the invention is defined in the appended claims.

Claims (83)

A polymer filter medium substantially free of perfluorinated polymer material, comprising:
The filter medium comprises a collection of fibers comprising an organic polymer;
The fiber has a diameter of about 0.03 to 0.5 μm;
The filter medium comprises a layer having a thickness of about 1 to 100 μm;
The filter medium, wherein the filter medium has a solidity of about 5% to 50%.   The filter media of claim 1, wherein the solidity is about 5% to 30%. The filter media has a thickness of about 5 to 100 μm and a flux greater than 10 mL / min / cm ² (10 mL-min ⁻¹ -cm ² ) of water at 10 psi. 2. The filter medium according to 1. Including two or more fiber layers, each fiber layer independently having a thickness of less than about 20 μm;
The filter media is at a flux greater than 10 mL / min / cm ² (10 mL-min ⁻¹ -cm ² ) of water at 10 psi and a flow rate of about 20 mL / min / cm ² of water. 2. The filter media of claim 1 having a filtration efficiency of at least about 98% for about 0.2 [mu] m particles. The fiber body has a thickness of about 5 to 80 μm;
The filter media is at a flux greater than 10 mL / min / cm ² (10 mL-min ⁻¹ -cm ² ) of water at 10 psi and a flow rate of about 20 mL / min / cm ² of water. The filter media of claim 1 having a filtration efficiency of at least about 98% for particles of about 0.2 µm. The solidity of the medium is about 7% to 25%;
The filter media is at a flux greater than 10 mL / min / cm ² (10 mL-min ⁻¹ -cm ² ) of water at 10 psi and a flow rate of about 20 mL / min / cm ² of water. The filter media of claim 1 having a filtration efficiency of at least about 98% for particles of about 0.2 µm.   The filter medium according to claim 1, wherein the filter medium is a wound medium or a pleated medium, and is combined with a porous support.   The filter media of claim 6, wherein the media comprises a media layer of a flat panel filter or a cylindrical filter.   The filter media of claim 1, wherein the fiber has a diameter of about 0.05 to 0.4 μm.   The filter media of claim 1, wherein the fibers comprise nylon fibers.   The filter media of claim 1, wherein the fiber comprises a polyolefin.   The filter medium according to claim 11, wherein the polyolefin includes polyethylene or polypropylene.   The filter media of claim 1, wherein the fiber comprises polyvinyl chloride.   The filter media of claim 1, wherein the fibers comprise polyacrylonitrile fibers.   The filter media of claim 1, wherein the fiber comprises polyethersulfone.   The filter media of claim 1, wherein the fiber comprises polyester.   The medium of claim 15, wherein the polyester comprises PET or PBT.   The filter media of claim 1, wherein the fiber comprises polyvinylidene fluoride.   11. The filter media of claim 10, wherein the fiber comprises a nylon fiber that includes a phenol adduct.   The filter media of claim 10, wherein the fiber comprises polycarbonate.   The filter media of claim 10, wherein the fiber comprises a styrene polymer. A polymer filter medium substantially free of perfluorinated polymer material, comprising:
The filter medium comprises at least two layers of organic polymer fibers;
The fiber has a diameter of about 0.03 to 0.5 μm;
A filter medium, wherein the at least two layers combine to form a body, the body having a thickness of about 2 to 100 μm and having a solidity of about 5% to 50%.   23. The filter media of claim 22, wherein the solidity is about 5% to 30%. Filter medium according to claim 22, characterized in that it comprises a water ^{10mL / min / cm 2 (10mL} -min -1 -cm 2) greater flux (flux) at 10 psi. Comprising two or more layers, each layer independently having a thickness of less than about 20 μm;
The filter media has a flux of about 15 to 60 mL / min / cm ² of water (60 mL-min ⁻¹ -cm ² ) at 10 psi and a flow rate of about 20 mL / min / cm ² of water. 23. The filter media of claim 22 having a filtration efficiency of at least 98% for particles of about 0.2 μm. The thickness of the body of the fiber is about 5 to 80 μm, the thickness of each layer is independently about 5 to 25 μm,
The filter media has a flux of about 15 to 60 mL / min / cm ² of water (60 mL-min ⁻¹ -cm ² ) at 10 psi and a flow rate of about 20 mL / min / cm ² of water. 23. The filter media of claim 22 having a filtration efficiency of at least about 98% for particles of about 0.2 μm. The solidity of the fiber body is about 7% to 25%;
The filter media is at a flux greater than 10 mL / min / cm ² (10 mL-min ⁻¹ -cm ² ) of water at 10 psi and a flow rate of about 20 mL / min / cm ² of water. 23. The filter media of claim 22, wherein the filter media has a filtration efficiency of at least about 98% for particles of about 0.2 [mu] m.   23. The filter medium of claim 22, wherein the filter medium is coupled to a porous support.   The filter media of claim 28, wherein the filter media comprises a flat panel media.   29. The filter medium of claim 28, wherein the filter medium includes a cylindrical medium.   24. The filter media of claim 23, wherein the fiber diameter is about 0.05 to 0.4 [mu] m.   24. The filter media of claim 23, wherein the fiber comprises a nylon fiber.   24. The filter media of claim 23, wherein the fiber comprises polyacrylonitrile fiber.   24. The filter media of claim 23, wherein the fiber comprises a nylon fiber that includes a phenol adduct.   24. The filter of claim 23, wherein the structure of the filter includes 3 to 5 layers of fiber, the body has a thickness of about 5 to 50 [mu] m, and each layer has a thickness of less than about 20 [mu] m. Medium. Filter medium according to claim 23, characterized in that it comprises a water ^{10mL / min / cm 2 (10mL} -min -1 -cm 2) greater flux (flux) at 10 psi. Comprising two or more layers, each layer independently having a thickness of less than about 20 μm;
The filter media has a flux of about 15 to 60 mL / min / cm ² of water (60 mL-min ⁻¹ -cm ² ) at 10 psi and a flow rate of about 20 mL / min / cm ² of water. 24. The filter media of claim 23 having a filtration efficiency of at least about 98% for particles of about 0.2 μm. The thickness of the fiber body is about 5 to 80 μm, and the thickness of each layer is independently about 5 to 25 μm;
The filter media has a flux of about 15 to 60 mL / min / cm ² of water (60 mL-min ⁻¹ -cm ² ) at 10 psi and a flow rate of about 20 mL / min / cm ² of water. 24. The filter media of claim 23 having a filtration efficiency of at least about 98% for particles of about 0.2 μm. The solidity of the body of the fiber is about 7% to 25%;
The filter media is at a flux greater than 10 mL / min / cm ² (10 mL-min ⁻¹ -cm ² ) of water at 10 psi and a flow rate of about 20 mL / min / cm ² of water. 24. The filter media of claim 23, having a filtration efficiency of at least about 98% for about 0.2 [mu] m particles.   24. The filter media of claim 23, wherein the filter media is bonded to a porous support.   41. The filter media of claim 40, wherein the filter media comprises a flat panel media.   41. The filter medium of claim 40, wherein the filter medium includes a cylindrical medium.   24. The filter media of claim 23, wherein the fiber diameter is about 0.05 to 0.4 [mu] m.   24. The filter media of claim 23, wherein the fiber comprises a nylon fiber.   24. The filter media of claim 23, wherein the fiber comprises polyacrylonitrile fiber.   46. The filter media of claim 45, wherein the fiber comprises a nylon fiber that includes a phenol adduct.   24. The filter media of claim 23, wherein the polymer fiber layer comprises a different polymer than the adjacent polymer fiber layer.   24. The filter media of claim 23, wherein the fiber layer has a different thickness than an adjacent fiber layer.   24. The filter media of claim 23, wherein the solidity of the fiber layer is different from the solidity of adjacent fiber layers.   24. The filter media of claim 23, wherein the fiber diameter is about 0.05 to 0.4 [mu] m. A filter medium substantially free of perfluorinated polymer material and substantially free of defect paths,
The filter media comprises at least two layers of polymer fibers;
The fiber has a diameter of about 0.03 to 0.5 μm;
The at least two layers are combined into one body;
The one body has a thickness of about 5 to 100 μm and a solidity of about 5% to 50%;
During the filtration of the liquid, the filtration of the liquid across the filter medium with a filtration action of at least 24 hours results in a flux of water of at least about 10 mL / min / cm ² (10 mL-min ⁻¹ -cm ² ) at 10 psi ( flux) and approximately 0.2 μm particles can be maintained at a filtration efficiency higher than 98.5% at a flow rate of approximately 20 mL / min / cm ² of water at approximately room temperature. Filter media.   52. The filter media of claim 51, wherein the solidity is about 5% to 30%.   52. The filter media of claim 51, wherein the fiber has a diameter of about 0.05 to 0.4 [mu] m. Comprising two or more layers, each layer independently having a thickness of less than about 20 μm;
The filter media has a flux of about 15 to 60 mL / min / cm ² (60 mL-min ⁻¹ -cm ² ) of water at 10 psi and a flow rate of about 20 mL / min / cm ² of water at about room temperature. 52. The filter media of claim 51, having a filtration efficiency of at least about 99% for particles of about 0.2 [mu] m at a flow rate. The fiber body has a thickness of about 5 to 80 μm, and each layer has a thickness of about 5 to 25 μm individually;
The filter media has a flux of about 15 to 60 mL / min / cm ² (60 mL-min ⁻¹ -cm ² ) of water at 10 psi and a flow rate of about 20 mL / min / cm ² of water at about room temperature. 52. The filter media of claim 51, having a filtration efficiency of at least 99% for particles of about 0.2 [mu] m at (flow rate). The solidity of the body of the fiber is about 7% to 25%;
The filter media has a flux of about 15 to 60 mL / min / cm ² (60 mL-min ⁻¹ -cm ² ) of water at 10 psi and a flow rate of about 20 mL / min / cm ² of water at about room temperature. 52. The filter media of claim 51, having a filtration efficiency of at least 99% for particles of about 0.2 [mu] m at (flow rate).   52. The filter media of claim 51, wherein the media is bonded to a porous support.   The filter media of claim 57, wherein the filter media comprises a flat panel media.   58. The filter medium of claim 57, wherein the filter medium includes a cylindrical medium.   52. The filter media of claim 51, wherein the fiber diameter is about 0.05 to 0.4 [mu] m.   52. The filter media of claim 51, wherein the fiber comprises a nylon fiber.   The filter media of claim 1, wherein the fibers comprise polyacrylonitrile fibers.   62. The filter media of claim 61, wherein the fiber comprises a nylon fiber that includes a phenol adduct.   52. The filter structure of claim 51, wherein the filter structure comprises 3 to 5 layers of fiber, the body has a thickness of about 5 to 100 [mu] m, and each layer has a thickness of less than about 20 [mu] m. Filter media. The filter media The filter media of claim 51, characterized in that it comprises a water ^{10mL / min / cm 2 (10mL} -min -1 -cm 2) greater flux (flux) at 10 psi. Comprising two or more layers, each layer independently having a thickness of less than about 20 μm;
The filter media has a flux of about 15 to 60 mL / min / cm ² (60 mL-min ⁻¹ -cm ² ) of water at 10 psi and a flow rate of about 20 mL / min / cm ² of water at about room temperature. 52. The filter media of claim 51 having a filtration efficiency of at least 98% for particles of about 0.2 [mu] m at (flow rate). The thickness of the fiber body is about 5 to 80 μm, and the thickness of each layer is individually about 5 to 25 μm;
The filter media has a flux of about 15 to 60 mL / min / cm ² (60 mL-min ⁻¹ -cm ² ) of water at 10 psi and a flow rate of about 20 mL / min / cm ² of water at about room temperature. 52. The filter media of claim 51, having a filtration efficiency of at least 98% for particles of about 0.2 [mu] m at a (flow rate). The solidity of the body of the fiber is about 7% to 25%;
The filter media has a flux greater than 10 mL / min / cm ² (10 mL-min ⁻¹ -cm ² ) of water at 10 psi and a flow rate of about 20 mL / min / cm ² of water at about room temperature. 52. The filter media of claim 51, having a filtration efficiency of at least 98% for particles of about 0.2 [mu] m at rate).   52. The filter media of claim 51, wherein the filter media is coupled to a porous support.   70. The filter media of claim 69, wherein the filter media comprises a flat panel media.   70. The filter medium of claim 69, wherein the filter medium comprises a cylindrical medium.   52. The filter media of claim 51, wherein the fiber comprises a nylon fiber.   52. The filter media of claim 51, wherein the fiber comprises polyacrylonitrile fiber.   74. The filter media of claim 73, wherein the fiber comprises a nylon fiber that includes a phenol adduct.   52. The filter media of claim 51, wherein the polymer fiber layer comprises a polymer that is different from an adjacent polymer fiber layer.   52. The filter media of claim 51, wherein the fiber layer comprises a thickness that is different from adjacent fiber layers.   52. The filter media of claim 51, wherein the fiber layer comprises a different fiber size than the adjacent fiber layer.   52. The filter media of claim 51, wherein the pore size of the fiber layer is different from the pore size of adjacent fiber layers.   52. The filter media of claim 51, wherein the solidity of a fiber layer is different from the solidity of adjacent fiber layers. A method of forming a filter medium, comprising:
(A) forming a layer having a thickness of about 1-100 μm on a substrate, wherein the fiber has a diameter of about 0.03 to 0.5 μm, the fiber comprising the substrate and a polymer solution; Forming a potential difference greater than 10 kilovolts, and
(B) separating the fiber from the substrate to form a layer;
(C) combining two or more layers of the fiber to form a filter body;
A method comprising the steps of:   The filter body is exposed to a pressure of at least about 5 psi at a temperature of at least about 100 ° C. to form a filter media having a thickness of about 5 to 100 μm and a solidity of about 5% to 50%. 81. The method of claim 80.   84. The method of claim 81, wherein the solidity is about 5% to 30%.   The body of fiber combines two or more layers of fiber to form the body, and the body is exposed to a calender roll at a temperature of about 100 to 250 ° C. and a pressure of about 15 to 100 psi, from about 7%. 81. The method of claim 80, wherein the method is formed by forming a solidity of 25% filter media.